Trading Charges Reach SAC

Federal prosecutors charged a Wall Street portfolio manager in what they described as the most lucrative insider-trading scheme ever, but their ultimate target appeared to be one of Wall Street's most successful and prominent investors: hedge-fund giant Steven A. Cohen.

The portfolio manager, Mathew Martoma, worked for an affiliate of Mr. Cohen's SAC Capital Advisors L.P. and was accused in criminal and civil complaints of obtaining...